The present invention relates to a vehicle sensor, and more particularly to a sensor attachment arrangement for vehicle air induction components.
Various types of air induction components such as air induction manifolds, air filter assemblies and throttle bodies are used in the field of internal combustion engines. Many known air induction components are presently manufactured of a non-metallic material such as nylon to simplify fabrication and reduce weight.
The prevalence of substantially non-metallic air induction components can create difficulties for the installation of sensors such as temperature sensors, manifold absolute pressure (MAP) sensors, mass air flow sensors, potentiometers and the like. Such sensors are commonly threaded directly into apertures in the air induction components. Other sensors include extended tabs which receive threaded fastener that enter the air induction components. However, these common attachment arrangements can create residue stress between the threaded sensor or fastener. During use, the air induction component heats up and the threaded sensor or fastener may tend to relieve the residual stress by moving away from its installed position. The sensor may then shift away from its original position and cause a degradation of performance.
Another known sensor attachment arrangement includes a barb which snaps onto a ledge. However, the known barb and ledge is relatively easy to disengage. A measure of a snap fit is the locking ratio which can be defined as the force to put the snap-fit in, divided by the force to take the snap fit object out. The locking ratio for the known barb arrangement is approximately 1:2. That is, it requires approximately twice as much force to remove the barb as to insert it. A low locking retention ratio is particularly disadvantageous when located adjacent a high-vibration vehicle component.
Known sensor attachment arrangements are also typically unique for each particular sensor. The unique attachment arrangements complicate manufacture of the air induction component and increases the difficulties of substituting sensors for different vehicle and engine types.
Accordingly, it is desirable to provide a sensor assembly which can be easily, securely and inexpensively attached to a non-metallic air induction component without the introduction of residual stress. It is further desirable to provide a generic attachment arrangement to simplify manufacture of the air induction component and allow the interchangeability of sensors.
The present invention provides a vehicle sensor assembly for a vehicle gas directing component such as an air intake manifold. The sensor assembly includes a retainer which digs into and locks the sensor assembly into a sensor receipt member.
The sensor receipt member is preferably formed into a vehicle gas directing component such as an air intake manifold. The sensor receipt member extends from an external wall of the gas directing component and provides an aperture into the interior of the gas directing component. The sensor receipt member preferably includes a frusto-conical outer surface which receives engagement members of the retainer.
In one disclosed embodiment the retainer is a cup-shaped member having a base and a wall extending substantially perpendicular from the perimeter thereof. A plurality of engagement members extend radially inward from the wall toward the base. The engagement members are therefore located substantially within the interior formed by the geometry of the retainer. Preferably, the sensor body portion can xe2x80x9cfloatxe2x80x9d within the retainer. By allowing the sensor body portion to float within the retainer, tolerance variations between the assembled parts are accommodated. To assure that the retainer places a substantially even load on the sensor body portion, a dimple is preferably formed in the center of the retainer base. The dimple faces the interior formed by the geometry of the retainer.
To install the sensor assembly, the sensor body is initially inserted within the aperture. The sensor assembly is then pressed into the sensor receipt member such that the engagement members engage the outer surface of the sensor receipt member. The engagement members provide a resistance toward the center of the sensor receipt member. Thus, since the retainer is preferably manufactured of a spring steel or a hard resilient plastic such as nylon, the engagement members attempt to return to their original position thereby locking the sensor assembly onto the sensor receipt member. Further, particularly when an extraction force is exerted upon the sensor assembly, each engagement member digs into the outer surface of the sensor receipt member.
In one disclosed embodiment, disassembly features are incorporated into the retainer. The engagement members are formed at a helical angle to engage thread-like features formed in the outer surface of the sensor receipt member. The sensor assembly can thereby be pushed on the sensor receipt member yet be easily removed by rotation thereby completing the thread forming. To further assist in removal, the wall of the retainer is preferably fabricated as a polygon to receive a tool or provide improved grip during manual removal.
A method for producing the sensor assembly preferably includes locating the sensor body within an initially cup-shaped retainer having a base and an extended wall. The next series of steps include progressively bending the wall toward a central first axis defined by the sensor body. Although a roller is illustrated in the disclosed embodiment it will be realized that other metal bending operations can be applied according to the present invention to form the retainer.
In yet another alternate embodiment, the sensor assembly includes an integral retainer. The sensor body preferably includes a longitudinal stepped wall that is thermally formed to fashion the engagement members.